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By Yoshio Nakano

Keywords: Tannin gel, Palladium, Separation, Redox We have developed the novel recovery system of palladium from wastes, which is simple and generates little secondary waste in comparison with the conventional recovery processes, using tannin gel particles synthesized from condensed-tannin molecules. Pd is adsorbed onto the tannin gel particles through inner-sphere redox reaction mechanism: two-electron transfer from tannin gel to Pd(II) species, accompanied by ligand exchange between chloropalladium(II) complexes and tannin molecules. In addition, we propose the separation system of Pd and Au from Pd-Au mixture, which is feasible due to the difference in oxidization and reduction potential between Pd and Au species: PdCl3(H2O)? and PdCl42? are less adsorbable than Pd species containing fewer Cl, such as PdCl2(H2O)2 and PdCl (H2O)3+, while such a distinct difference between Au species is not observed.

Jan 1, 2005

By Aline Maria dos Santos Teixeira

Serpentinite is an ultra basic and metamorphic rock consisting mainly of magnesium, calcium and silicon oxides. The rock under study is a host rock of chromite mine located in Andorinha, BA. The objective of this paper is to evaluate the rock's physical and chemical characteristics to be used as an additional fertilizer of acid soils. After comminution, rock samples were submitted to chemical analysis, XRD, SEM-EDS and TGA. Afterwards, particle size distribution was determined. Result analysis confirms that our rock consists mainly of dolomite, calcite and diopside. According to the result obtained, it can be said that the serpentinite rock has promising applications in agriculture for the correction and additional fertilization of acid soils. However, it is necessary to study the characteristics of the rock such as its dangers and toxicity as well as evaluate them according to the legislation for corrective acidity.

Jan 1, 2010

By Xiang-yang Zhou

Keywords: Low-Grade Dolomite, Low CaO Content, High Specific Surface Area, MgO. A low energy consumption preparation technology of magnesium oxide with low calcium oxide content and high specific surface area from low-grade dolomite has been investigated. The optimum technical conditions for the preparation of magnesium oxide are the followings: dolomite is partially calcined at 750-800° for 2 h; the optimum solid-liquid ratio range in calcined dolomite slurry is 20-30 g?l?1; carbonation temperature, carbon dioxide pressure and end point pH value of carbonation are less than 40°, 0.4-0.6 MPa and 7 respectively during carbonation process; decomposition temperature of Mg(HCO3)2 solution is near 100°; calcination temperature of the precursor (i.e. precipitated basic magnesium carbonate) is less than 850°. More than 90% of magnesium can be extracted by the technology. The MgO product (CaO < 0.38%) with a specific surface area of near 50 m2?g?1 also can be obtained by the technology.

Jan 1, 2005

By D. Death

The Tapping Camera Prototype (TCP) is an instrument being developed to record and analyse video of the molten metal stream entering a tapping crucible as it is tapped from an aluminium reduction cell. The development aims to provide potroom floor operators with continuous real time vision of the tapping process and provide an alert in the event of excessive bath contamination in the extracted metal stream. Longer term the system may provide sufficient data to enable control of the tapping process. The TCP mounts a wireless camera and periscope to view the molten metal stream via a peephole in the tapping crucible. Real time video is recorded to either digital video tape or computer disk for subsequent video analysis to quantify the bath material drawn into the tapping crucible with the molten aluminium. The images transmitted by the camera are available on a handheld LCD video screen. This work is an initiative of the CSIRO?s Light Metals Flagship.

Jan 1, 2006

By F. Kavicka

An original application of ANSYS simulated the forming of the temperature field of a massive casting from ductile cast-iron during the application various methods of its cooling using chills. The numerical model managed to optimize more than one method of cooling but, in addition to that, provided serious results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the pouring structure. The file containing the acquired results from both models brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity and the local solidification time in any point of the casting. The determined relations therefore enable the prediction of the face density of the spheroids of graphite in dependence on the local solidification time. The calculated temperature field of 500x500x1000 mm casting of ductile cast-iron with various methods of cooling has successfully been compared with temperatures obtained experimentally. Acknowledgments. This analysis was conducted using a program devised within the framework of the GA CR projects (No.106/04/1334, No. 106/04/1006 and No. 106/04/094), of the COSTAPOMAT-OC526.10, MPO/FI-IM/021, EUREKA No.2716 COOP and KONTAKT 14/ 2005/06.

Jan 1, 2006

By Y. F. Liang

Fe-6.5wt.%Si alloy has excellent soft magnetic properties compared with conventional silicon steel. It is very brittle at room temperature due to appearance of ordered phases, like B2 and DO3. In this paper, we investigate the effect of ordering on cold workability of this alloy. Methods of rapid quenching and hot rolling were utilized. It is found that rapid quenching and proper heat treatment of the hot rolled sheet could decrease the degree of order due to the very high solidification rate and high cooling rate. The rapid quenched sheet and hot rolled sheet after proper heat treatment could be cold rolled without crack. Microstructure, phase ordering, micro hardness, and cold rolling properties were investigated by Optical Microscope, X-ray Diffraction, Micro Hardness Indenter and Four-high Mill.

Jan 1, 2009

By Cajsa Samuelsson, Theo Lehner

Converting and refining play a central role in the extraction of metals. Sweden has a long tradition as an experimental play ground for metallurgists, chemists and alchemists, developing new methods and technologies. Presenters of papers are usually happy in recording successful developments. But reporting failures can be as great a value as the former. In the paper experiments and experience in process development are illustrated, differences between ferrous and non-ferrous developments are highlighted and industrial learning curves are discussed. 53

Jan 1, 2009

By Khandaker M. Anwar Hossain

This paper presents the development of lightweight concrete (LWC) incorporating pumice aggregate and volcanic ash (VA) based ASTM Type I blended cement (PVAC). Fresh and mechanical properties of LWC mixtures such as slump, air content, compressive strength, tensile strength, density and modulus of elasticity are described. The durability characteristics are investigated by drying shrinkage (DS) and water permeability. The investigation suggests the production of LWCs incorporating blended PVAC and VPA having satisfactory strength/durability characteristics for structural applications. The use of PVAC induces the beneficial effect of reducing drying shrinkage and water permeability. Development of such non- expensive and environmentally friendly LWCs with acceptable strength and durability characteristics is extremely helpful for the sustainable development and rehabilitation of volcanic disaster areas around the world.

Jan 1, 2010

By Elsa Olivetti

Life cycle assessment (LCA) is used increasingly as a tool to provide quantitative metrics of environmental impact and inform early stage materials selection decisions. One common challenge in LCA stems from allocation of burden when multiple adjacent products share some of the same processes. A critical example of this is the partitioning of benefit or burden at product disposition in open-loop recycling scenarios. This work reviews the challenge of allocation and investigates the various methods proposed for allocating end-of-life (EOL) burden. Specifically this work examines whether these methods lead to different results and explores the trends in allocation method bias for or against particular materials classes.

Jan 1, 2010

By Dale A. Zuck

Recovery of aluminum metal from drosses? is a major factor in the recyclability success story enjoyed by the United States aluminum industry. Today&apos;s modern dross processor uses the latest technology to maximize metal recovery at the lowest cost while complying with all environmental laws and regulations. Most dross processors, however, pay little attention to the resulting saltcake, the end residual of dross recyCling, and rely on landfills for .disposition of this material.. The alternative is to recycle the saltcake, but the success of this technology is dependent on the development of reliable outlets for each of the saltcake constituents. This paper discusses the evolution of an aluminum dross oxide processing technology that ,produces an economically attractive source of alumina for the production of portland cement.

Jan 1, 1995

By Ailton da Silva Ferreira

Thermoset polymers, like the polyester, become harder with increasing temperature owing to molecular crosslink formation, which is a thermal benefit for composite matrix applications. Natural lignocellulosic fibers, however, have low thermal resistance and tend to degrade with increasing temperature. Therefore, the combination of a lignocellulosic fiber, as reinforcement, with a thermoset polymer, as the matrix, results in a composite material with complex thermal behavior. In the present work, a thermal analysis was conducted on polyester composites with different amounts of curaua fibers. Both TGA and DTG curves were analyzed to determine the effect of the curaua fiber on the thermal resistance of the composites. It was found that the curaua fiber sensibly affects the thermal behavior of the polyester matrix for fiber amounts above 10% in volume. This effect is associated with an increase in thermal degradation.

Jan 1, 2010

By Helvio Pessanha Guimarães Santafé Jr.

The coir fiber extracted from the husk of the coconut has been extensively used as polymer composite reinforcement in a variety of industrial applications ranging from civil construction to automobile seat cushions. The hydrophilic coir fiber does not act as an effective reinforcement owing to its low interfacial strength with hydrophobic polymers. As a consequence, coir fiber composites display relatively low mechanical strength. The objective of this work was to investigate the effect of an acetylation treatment of the coir fiber surface on the mechanical behavior of epoxy composites with amounts of fibers up to 30% in volume. Coir fibers were immersed in an acid solution of acetic anhydride for one hour, washed and dried, before mixing with DGEBA/TETA epoxy to fabricate the composites. Flexural mechanical properties were obtained by bend tests. The results showed significant differences to similar composites with alkali treated coir fibers that have been previously investigated.

Jan 1, 2010

By Mark Osborne, Ray D. Peterson, C. Edward Eckert

"The theoretical melting energy requirement for a typical hypoeutectic aluminum-silicon alloy is approximately 520 BTU/lb. It has been demonstrated, however, that even a state of the art secondary processing-automated lost foam casting operation can exceed this value by at least an order of magnitude when the actual thermal energy input from melting to solidification is monitored. Metal transfer and holding operations constitutes over 65% of this expenditure. The authors present relative benchmark energy expenditure information by unit operation for an offsite melting/lost foam casting line with a daily throughput in excess of 100,000 lbs. Efficiency improvements through optimization of the current process, and anticipated energy values at the culmination of a U.S. Department of Energy sponsored project to develop, integrate and demonstrate an advanced melting, transportation, and dispensation system will be cited.IntroductionThe size of the U.S. aluminum remelt pool was approximated to be 14.21 billion kg (31.27 billion pounds) by a recent study?, with the engineered castings (foundry) sector accounting for 3.25 billion kg (7.16 billion pounds) or 23% of that total. This study considered overall process yield and all major contributors to scrap. The values cited, therefore, are more meaningful than simply tabulating annual pounds shipped by sector.The foundry sector consists of Sand Castings, PM Castings and Die Castings categories appearing in Figure 1. All other categories comprise the wrought alloy sector. Wrought alloy production enjoys an energetic benefit from both scale and a relatively continuous operation. Many foundry operations, however, operate in batch mode at less than design metal throughput with characteristically longer melt holding periods. Since any detention of molten metal beyond melting represents an overhead use of energy, melt holding (secondary) energy expenditures can appreciably inflate melting energy requirements in the foundry."

Jan 1, 2009

By Daudi R. Waryoba

Keywords: Wire Drawing, OFHC Copper, Recrystallization, Orientation imaging Microscopy (OIM), Texture inhomogeneity Textural inhomogeneities have been investigated in oxygen free high conducting (OFHC) copper wire drawn at room temperature to a true strain of 2.31, and isothermally annealed at 250°C and 750°C for annealing times ranging from 10 s to 1 hr. Local orientations were mapped by means of orientation imaging microscopy (OIM). The microtexture of the drawn wires showed a strong <111> + weak <100> duplex fiber texture at the inner core, whereas the mid and surface regions had a comparatively weak texture. Annealing at 250°C resulted into a recrystallization which originated from the mid section, proceed towards the surface regions and ends in the inner core. Recrystallization resulted into a strong<100>+weak<111> duplex fiber texture. A similar textural inhomogeneity was observed during short annealing at 750°C. However, prolonged annealing gave rise to abnormal grain-growth that proceed from the inner core to the outer surfaces with a dominant <111> fiber component at the inner region and mixed components of <111>, <100>, and <112> at the outer surfaces.

Jan 1, 2005

By Joner O. Alves

The disposal of scrap tires has been a serious environmental problem. The treatment of this waste by pyrolysis and combustion has advantages since the landfill space is dwindling and the production of fuel becomes of technological interest. However, that processes needs a rigid control of emissions. This work presents a study of the light hydrocarbon gases (HC) generated during the burn of waste tire chips in a two-stage laminar-flow horizontal furnace. Different temperatures in the primary and secondary stage of the furnace were tested, and the oxygen/nitrogen percentage was also varied during the combustion process. A gas chromatograph was used to identify and quantify the components of the gaseous products of combustion and pyrolysis. The results showed the behavior of the gases during the burn of tires, providing valuable information to the control of hydrocarbon emissions.

Jan 1, 2010

By A. G. Merma

In this work, the electrocoagulation technique was studied in order to treat chemically stabilized concentrated oil-water emulsions. This study was mainly focused on the effects of operating parameters such as initial pH, current density, reaction time, electrode distance and inlet concentration on the separation of oil as measured by the chemical oxygen demand -1(COD) method. The synthetic emulsion was prepared from Shell - Talpa 30 oil (3g.L-1) and sodium dodecyl sulfate (1.0 g.L), having a Zeta potential around -70 mv at pH 8.7. The process was carried out in an electrocoagulation cell with a set of four parallel monopolar electrodes. This set consisted of two aluminum plate anodes and two 316L stainless steel plate cathodes. Kinetic curves showed that the electrocoagulation process exhibits three phases: (1) an initial phase, where the COD did not decrease because the solution had not reached the minimum amount of dissolved aluminum required to cause the break-up of the emulsion, (2) a reactive phase during which COD decreased due to possible agglomeration of the precipitates and (3) a steady-state phase where the COD did not change. The results showed that the period to reach the reactive phase decreased as the current density increased and the pH values decreased.

Jan 1, 2009

By Run Huang, Xuewei Lv, Songli Liu, Chenguang Bai

"Titanium alloy was prepared from titania-bearing blast furnace slag (Ti-BF slag) by aluminothermic process in an induction furnace. The effects of aluminum amount on the titanium silicon yield and titanium recovery ratio were studied. The phase transformation and chemical composition of the prepared alloy were investigated by X-ray diffractometry (XRD) and X-ray fluorescence (XRF) respectively. It was found that the mass fraction of silicon and aluminum increased with increasing the aluminum amount, however, the mass fraction of titanium increased first and then decreased with increasing the aluminum amount. Furthermore, both the titanium alloy yield and titanium recovery ratio increased with the increase of aluminum amount. The main phases of the alloy were TixSiy and AlTi3. The titanium alloy samples prepared in various conditions had a composition (wt.%): 38–50% Ti, 29-34% Si, 4-11 Al%, 1.6-2.2 Mn%.IntroductionPanzhihua and Xichang regions in the southwest of China are rich in vanadium-titanium magnetite containing iron, vanadium, titanium and gangue. According to the characteristics of the resource, iron and vanadium are successfully recovered with a blast furnace process and a converter process. However, most content of titanium are entered in the blast furnace slag with TiO2 22% -26% and metallic Fe 2%–6% called Ti-BF slag. Due to the dispersed distribution of Ti in various fine grained mineral phases with a complex combination between Ca, Al and Si, it is difficult to recover the Ti components[1]. This slag is generated at a current rate of 3.6 million tons per year, which adds to the existing 70 million tons of slag produced so far[2]. The slag has had to be piled as large as the mountains, which not only waste of resources but also cause a pollution of the environment. Therefore, the study of integrated utilizing Ti-BF slag has become very significant."

Jan 1, 2012

By Gabrielle Gaustad

For aluminum, substitution of primary with secondary resources decreases energy consumption; this energy advantage creates a strong economic incentive to recycle. Several authors have raised concerns that the current sinks for secondary materials may soon be saturated, impeding subsequent expansion of recycling. This work combines dynamic material flow analysis with optimal batch planning models to quantify the significance and drivers of these pending limits under several scenarios, and thereby explore potential opportunities to increase recycling. An aluminum recycling system case was developed that includes containers and packaging, automotive, and construction products and scraps. The impacts on aggregate scrap utilization and materials cost are explored in the context of changing alloy demand and lifetime. Insights drawn from this specific case study could be applied to multi-stakeholder, systemic models.

Jan 1, 2010

By Ram Avtar

High tensile thick plates (>80mm, weight ~3000 Kg) of medium carbon low alloy steel, when heat treated, manifested higher percentage of crystalline area (>20%) in fractured surface. Such problem was not encountered in thinner plates. The genesis of higher crystallinity in fracture was examined. It was observed that the thicker plate undergone slower rate (Average 0.9oC/Sec.) from soaking temperature to Ms temperature) of cooling after austenising during oil quenching and thereby quenched microstructure had upper bainites. During tempering of as quenched bainite, additional precipitation took place at the lath boundaries of bainite. This led to weakening of grain boundaries and aided easy crack propagation during fracture and resulted in formation of higher percentage of crystalline area in fractured surface. Enhancement in cooling rate (Average 1.8oC/Sec. from soaking temperature to Ms temperature) of austenised plate by switching over from oil quenching to water quenching practice resulted in complete transformation of austenite into martensite and produced ductile fracture (zero Crystallinity). Plates conformed improvement in mechanical properties between 2-5%.

Jan 1, 2009

By José Carlos D?Abreu

The Tecnored process is a new ironmaking technology, developed on a unique approach that combined empirical and theoretical knowledge backed by extensive tests carried out in a dedicated pilot-plant and with close support of universities and research centers. Campaigns in the pilot-plant focused on operate different reactors of different sizes, including a full size slice of the industrial furnace. This approach provided actual conditions to develop the main features of the process such as the internal dimensions, raceway pattern, thermal and gaseous profiles, etc, besides provide reliable data to feed and calibrate a specific mathematical process modeling. This paper presents the first computer model used by the Tecnored technical staff, focusing the behavior of a self reducing agglomerate in the upper shaft of the furnace (zone of solid state reduction). Some results of this model are given and discussed.

Jan 1, 2006